Interfacial Solder Fracture Does Not Necessarily Mean Black Pad

What the evidence preview establishes

The expected black-pad indicators were absent. Brittle interfacial fractures were instead associated with severe board delamination and limited board-side intermetallic development, supporting mechanical loading potentially aggravated by marginal reflow.

Why this case matters

Diagnose black pad from its metallurgical indicators, not from joint separation alone. Board delamination and asymmetric intermetallic growth can redirect the investigation toward mechanical and reflow history.